Mercedes E Class Estate rear air suspension problem
Discussion
So I had the pleasure of finding out there was a problem with my rear airmatic suspension as I driving home and the ride felt very bouncy on my way to get some new tyres fitted. Pulled over and found that the rear suspension was completely dropped. If anyone else has these problems I've got a few tips on how to fault find and hopefully not to get ripped off. Note, it's usually aN electrical fault, or a physical fault. Faults like air leaks may be thrown up on an laptop but it won't tell you the component that is leaking. Halfords tried to con me into buying an air bag because "their laptop told them it was leaking" which would have cost £650 plus! Luckily for me I'm a mechanic so I thought I better check first. Firstly, if it's an electronic fault you should have a fault code or message on the dash, if so any fault will be picked up using a diagnostic laptop to make diagnosis a lot easier. If you can't access a laptop follow these 3 steps.. 1. Check the fuses in the fuse box located in the boot behind the side net (There is a relay and fuse 68). 2. Check if you can hear the pump working (very fast ticking sound) located near the rear bumper. If not you will need to access it and check for a main voltage going to the pump, a signal voltage (different smaller plug) and a good earth on both lumes. If the pump and power to the pump is fine, then the likely cause is the.. 3. height level sensors. They are located near the air bags. They might be faulty so to test them you can disconnect them, and operate them by hand whist checking resistance. An open line will indicate an unserviceable sensor. If you suspect it isn't an electrical fault, there are 2 main faults to check. 1. check for air leaks on pipes, unions, and air bags (self explanatory) and 2. Check the level sensor moving parts. The rod connecting the sensor to the chassis had broken on mine so I ordered a new 1 off eBay for 20 quid, fitted it myself in about an hour and saved a small fortune ☺
I've just had the pleasure of rear suspension shenanigans on a W212 (2010 E-Class estate).
In my case I put a sofa in the back. Something about that amount of load meant the suspension changed to the point where it must not have been previously. We usually have two kids in the back but have also filled it for the dump, moved house and carried adults on the rear seats... including in the boot on one occasion. All pretty similar to a sofa... but there must be something about this particular load.
I had to get the car recovered and as an ex-mechanic that is a terribly painful experience as I know what's wrong with the car and could fix it if it were in my workshop!
First of all the suspension rose up to the maximum height. I parked, turned off, got out... drove it a bit and it settled down again. Then it decided to re-inflate to the maximum height once more. This time it wouldn't calm down. I continued to drive with the rear air bags fully extended. Next thing I heard the sound of a big air leak and the rear suspension lost all its height completely.
I don't have the car back yet... but on initial inspection at the roadside I can see the pipe broken off the airbag and you can hear the air leaking. The dashboard says 'raising vehicle, please wait' (or words to that effect).
After some research there seems to be a common fault with the ball-joint on the suspension level sensor rusting causing the plastic arm to snap. So what started as a sensor fault turned into an air-leak. My hope is that if I fix both problems it'll be more-or-less a free fix. But I won't know until I get under it. Will report back for other people having the same issue... apparently it's quite common. But once fixed it is fixed.
In my case I put a sofa in the back. Something about that amount of load meant the suspension changed to the point where it must not have been previously. We usually have two kids in the back but have also filled it for the dump, moved house and carried adults on the rear seats... including in the boot on one occasion. All pretty similar to a sofa... but there must be something about this particular load.
I had to get the car recovered and as an ex-mechanic that is a terribly painful experience as I know what's wrong with the car and could fix it if it were in my workshop!
First of all the suspension rose up to the maximum height. I parked, turned off, got out... drove it a bit and it settled down again. Then it decided to re-inflate to the maximum height once more. This time it wouldn't calm down. I continued to drive with the rear air bags fully extended. Next thing I heard the sound of a big air leak and the rear suspension lost all its height completely.
I don't have the car back yet... but on initial inspection at the roadside I can see the pipe broken off the airbag and you can hear the air leaking. The dashboard says 'raising vehicle, please wait' (or words to that effect).
After some research there seems to be a common fault with the ball-joint on the suspension level sensor rusting causing the plastic arm to snap. So what started as a sensor fault turned into an air-leak. My hope is that if I fix both problems it'll be more-or-less a free fix. But I won't know until I get under it. Will report back for other people having the same issue... apparently it's quite common. But once fixed it is fixed.
I've got the car back from the recovery company and bizarrely it looks like they plugged the hose back into the airbag. The car is back up on stilts. So there's still something for me to fix but at least it looks like someone had a go at the air leak.
I can see it being advantageous to them to get the car off it's arse for moving on and off recovery trucks. I'm also aware there is a type of air bag with a push-fit connector.
A lot of assumptions on my part but I did point it out to the recovery driver that the hose had come off the airbag.
More to follow once I've had a chance to look under it.
I can see it being advantageous to them to get the car off it's arse for moving on and off recovery trucks. I'm also aware there is a type of air bag with a push-fit connector.
A lot of assumptions on my part but I did point it out to the recovery driver that the hose had come off the airbag.
More to follow once I've had a chance to look under it.
Common problem. We battled with ours for a while as the suspension dropping overnight was intermittent. I changed the control unit behind the rear bumper (as it was a cheap potential fix) to no avail. Bit the bullet and had both rear air bags replaced along with the pipes. Not had a problem since.
Just seen this thread and I have a related issue. 8 times out of 10, I'll come back to the car after it's been standing overnight and it's dropped right down at the back. Start the car, it rises to the correct height and feels fine. Am i right in thinking this is probably a sensor.I'm thinking if it was a leak, it would drop all of the time and not rise ? I also tow and it holds the height when trailered up no problem...
Dropping at rest is a leak. If its intermittent its probably on one of the bags. They often split in the overlapped section where grit gets trapped and wears through the rubber. Depending on the resting position of the suspension the hole may not always be exposed to lose air.
If you’ve got a leak you’ll be working the compressor much harder than normal so better to get it sorted sooner rather than later.
If you’ve got a leak you’ll be working the compressor much harder than normal so better to get it sorted sooner rather than later.
Inspectorclueso said:
Just seen this thread and I have a related issue. 8 times out of 10, I'll come back to the car after it's been standing overnight and it's dropped right down at the back. Start the car, it rises to the correct height and feels fine. Am i right in thinking this is probably a sensor.I'm thinking if it was a leak, it would drop all of the time and not rise ? I also tow and it holds the height when trailered up no problem...
Exactly the same as ours was and we also tow quite a heavy caravan. It'd drop overnight (worse when it was really cold) but raise in the morning and be fine. I worried about an air bag failing whilst towing with the children in the car so i replaced both and some pipe work. It's been perfect ever sinceCan I just point out the obvious logical irregularity in the idea of both bags failing together.
The system has many points on it which can be a single point of failure which will deflate both bags and if both sides have dropped at the same time it is certainly not because both bags have to be replaced.
Anyone who has a small leak which causes it to lose pressure overnight should carefully check all the pipework and valves rather than jump to conclusions.
The system has many points on it which can be a single point of failure which will deflate both bags and if both sides have dropped at the same time it is certainly not because both bags have to be replaced.
Anyone who has a small leak which causes it to lose pressure overnight should carefully check all the pipework and valves rather than jump to conclusions.
PASMERC said:
They do suffer with a few problems, rear air bags leak, rear air lines crack and the wiring chafes by the air pump
Chafed wires will see a total failure. On a car with good bags and no other problems it'll lower itself to the deck over the course of several days / week as the air leaks but fails to refill due to electrical fault. You'll see the warning on the dash long before the suspension loses all its height. Gassing Station | Mercedes | Top of Page | What's New | My Stuff